Integrated circuits are widely used in many types of electronic equipment. An integrated circuit may include a silicon substrate in which a number of active devices, such as transistors, etc., are formed. It is also typically required to support one or more such integrated circuits in a package that provides protection and permits external electrical connection.
As the density of active devices on typical integrated circuits has increased, dissipation of the heat generated has become increasingly more important. Designers have developed cooling techniques for integrated circuits based on micro-electromechanical (MEMs) technology.
For example, as shown in FIG. 1, a prior art electronic device 10 includes a package 11 including a first member 12 comprising silicon, and a second member 14 comprising a low temperature co-fired ceramic (LTCC) material. The first member 12 may include several stacked silicon substrates 12a, 12b having various components of a micro-fluidic cooler formed therein. For example, as shown in the illustrated embodiment, an evaporator 16 and condensor 17 may be provided and interconnected via one or more micro-fluidic channels or passageways 21 formed between the silicon substrates 12a, 12b. One or more MEMs pumps, not shown, may circulate the cooling fluid.
The second member 14 may also include several LTCC layers 14a, 14b laminated together as shown in the illustrated embodiment. The second member 14 also illustratively carries an integrated circuit 22, such as an insulated gate bipolar transistor (IGBT) or other integrated circuit that may typically generate substantial waste heat. The second member 14 also includes external connections 23 which are connected to the electrical connections 24 of the integrated circuit 22 via the illustrated wires 25.
As shown in the enlarged view of FIG. 2, the integrated circuit 22 is carried by a receiving recess 27 in the second member 14. A series of micro-fluidic passageways 30 may be provided through the LTCC member 14 adjacent the integrated circuit 22 to deliver cooling fluid thereto.
Typically, the LTCC member 14 and the silicon member 12 are adhesively joined together as schematically illustrated by the adhesive layer 31. Thermoplastic and/or thermosetting adhesives are commonly used. Metal layers may also be used. Unfortunately, the adhesive layer 31 has a number of shortcomings. The adhesive layer 31 may not typically provide a hermetic seal at the interface between the silicon and LTCC, thus, cooling fluid may be lost. In addition, the adhesive layer 31 may also provide yet another layer through which the heat must pass. Of course, it may be difficult to provide an adhesive layer 31 which is uniform and which does not protrude into the interface or otherwise block or restrict the flow of cooling fluid. In other words, such an adhesive layer 31 unfortunately provides only non-hermetic and non-uniform bonding the members.
U.S. Pat. No. 5,443,890 to Ohman discloses a leakage resistant seal for a micro-fluidic channel formed between two adjacent members. A sealing groove is provided and filled with a fluid sealing material which is compressed against adjacent surface portions of the opposing member. The provision for such a sealing structure requires additional manufacturing steps and may not be suitable for many applications.